What is it when your video card makes noises?

I've noticed this with all my video cards, but its been particularly noticeable with my gtx 780 sc. the card can be pretty much silent most of the time in games, but then a look a particular corner or the floor/ceiling and my card starts making noise. and then it goes away the moment i look away. not a grindy or rattling noise, but certainly sounds different. is that just the fan kicking in at different speeds or something?

Probably coil/cap whine if it sounds like an electrical noise. If not then yeah probably the fan.

More than likely fan, if the card works harder the fan will run faster, my 7850 does it too

It strikes me that you're experiencing a "frequency" thing by your description. You might check this out: https://www.youtube.com/watch?v=HP73edpQwgc

It's a Linus tech tips link and one of the better demonstrations of coil whine I've seen.